Method of making a glass reinforced fibrous web



Dec. 3, 1963 c. DONALDSON 3,113,061

METHOD OF MAKING A cuss REINFORCED FIBROUS WEB Filed Jan. 4. 1961 mi zzvrox (Hess Do/Jfiwsou HTTOENE Y United States Patent 3,113,661 METHUD 0F lvlAlilNG A llElNlFfllllIED Willi Chase Donaldson, Mount Vernon, N.Y., assign'or to Darworth, incorporated, a corporation of Connecticut Filed den. 4, 1961, S81- No. $9,631 4 Qlaims. (til. 156-167) This invention is directed to a glass reinforced fibrous web and method of making the same.

The primary object of this invention is to make a glass reinforced fibrous continuous web of undeterminate length, wherein the fibrous web is preferably formed mainly of a body of asbestos fiber and to combine with such a fibrous web closely spaced apart continuous glass filaments applied to the web while the glass is in nascent state and extending longitudinally of the web, so as to produce as an end product a substantially homogeneous reinforced fibrous web, wherein all portions of the web and glass filaments are completely impregnated and bound together in a homogeneous structure by thermosetting resinous material. This invention provides a web of indeterminate length useful in the fabrication of pipes, tubes, and other products by the wrapping of the reinforced web about a suitable mandrel or mold and using either the entire width of the web or slitting the web longitudinally into tapes which are in turn wound as stated.

In practically carrying out the invention in its preferred form, a fibrouus web, e.g., an asbestos web, such as disclosed in I. I. Novak United States Patent No. 2,626,213 of January 20, 1953, is thoroughly impregnated with a thermosetting resin preferably in uncured or partially cured condition. As this web is caused to travel along a predetermined path, glass filaments are fed from a succession of furnaces spaced apart longitudinally of and above said path. As the filaments are fed from the furnaces through conventional bushings, an appropriate coupling agent and resinous material is applied to these filaments to insure proper cohesion between them and the impregnated web.

The several furnaces remain stationary and the filaments are fed from these successive stationary furnaces in laterally spaced relation with respect to the filaments fed from the preceding furnaces. By this method relatively fine glass filaments may be applied to the web in closely spaced apart relation and with remarkable uniformity of such spacing and all of the filaments will be parallel to one another and to the edges of the web, so as to impart to the finished web maximum longitudinal tensile strength.

In practice, pressure is applied to the filaments after they have been laid upon the web, so that uniform con tact between the web and filaments will result, with all of the filaments occupying the same transverse plane.

I am aware that glass filament reinforced resin webs have heretofore been made by feeding glass filaments from a furnace to a rotating drum and impregnating these filaments with resinous material. After the desired number of plies of such filaments have been wound upon the drum the winding operation is discontinued and the resulting laminate is removed from the drum by cutting it longitudinally of the drum to produce the end product web. With this procedure the furnace is reciprocated axially of the drum and the filaments are thus deposited on the drum along helical paths, so as to obtain the desired lateral spacing of successive convolutions of the filaments. When filaments are thus fed, the resulting web does not embody filaments which are parallel to one another and to the lateral edges of the web. Consequently said web does not have the same longitudinal strength or fixed longitudinal dimension as when the filaments are parallel to one another and to the lateral edges of the web. Moreover, under such prior practice the diameter of the drum determined the length of the web, whereas in accordance with the present invention, the end product is a glass reinforced resin impregnated fibrous web of indeterminate length. That is to say, it may be made in any length desired.

In accordance with this invention, the glass filaments are fed and applied to a pre-impregnated fibrous web running very close to the bushings of the several furnaces, so that these glass filaments are applied to said web while the glass is still in hot nascent state for I have found that it is in this state and condition that the best results are obtained.

Features of the invention, other than those adverted to, will be apparent from the hereinafter detailed description and appended claims when read in conjunction with the accompanying drawing.

The accompanying drawing i.lustrates one practical embodiment of the invention, but the construction therein shown is to be understood as illustrative, only, and not as defining the limits of the invention.

The drawing is a perspective view illustrating apparatus according to this invention and the several steps of the method involved in the making of the end product of this invention.

Referring to the drawings, 1 designates a roll comprising a web w of any appropriate fibrous material, such as paper or asbestos fiber, which web, before being formed into the roll 1, has been thoroughly impregnated with a thermosetting resinous material, such, for example, as an epoxy, polyester, Juton, or phenolic resin. This web is fed from the roll 1. to and over a drum 2 which is preferably heated and, from the drum 2, over any appropriate number of supporting rolls 3 to a take-up roll The several rolls and the drum are supported on appropriate standards 5.

As the web w is wound upon the take-up roll 4, there is preferably fed between the successive convolutions of the web, from a roll 6, an inter layer 7 which serves as a parting medium between the several convolutions of the web, so that these convolutions will not cohere with one another. This inter layer may be of polyethylene or any other suitable material.

Arranged in spaced apart relation above and longitudinally of the web are a plurality of glass supplying furnaces Fl, F2, F3 and F4, any number of a plurality of which may be employed without departing from this invention. These furnaces are conventional and each is provided with a conventional bushing through which molten glass filaments of the desired size may be fed. in practice, they may be of the order of .0007 or as low as .09035 in diameter. in fact, the diameter of these filaments may be very small, although they may be of greater diameter if so desired.

As the preimpregnated fibrous web travels along its predetermined path, the filaments from the several furnaces in succession are fed through conventional bushlugs and deposited directly upon the web at a speed corresponding to the speed of the web. It should be noted in this connection that in accordance with this invention glass filaments are fed from the bushing to the web in contradistinction to the feed of yarns to the web. These filaments may be of any appropriate size for the particular end use to which the finished Web is to be put and consequently their diameter may be somewhat larger if desired than is ordinarily the case of individual filaments which are subsequently collected into the yarn and fed 1? I generally employ speeds comparable to those heretofore employed in the feed or" filaments onto a drum as hereinbefore described, i.e., for example, 1,0(ltl2,500 ft. per minute rate of travel of the web.

The bushings of each of the several furnaces are so spaced and located transversely of the web that the bushings of each furnace are staggered relative to the other furnaces, whereby the filaments successively fed to the web as the latter travels are closely spaced apart from one another transversely of the web. The filaments fed from each successive furnace are thus inter-spaced between the filaments fed from preceding furnaces. By this arrangement, it is possible to lay onto the web extremely fine filaments closely and uniformly spaced apart transversely of the Web but extending continuously for the full length of the web as the l tter is fed to and rolled upon the take-up roll 4'. 7

It is essential to the best results in carrying out this invention that there be obtained a strong and permanent bond between the several filaments and the fibrous web. Accordingly, I preferably apply tothe filaments of each group, as they issue from the bushings of the furnaces, a coupling agent and resinous material which are compatible with the resin with which the web is pre-iinpreg nated. When such a procedure is followed, the several filaments, upon contact with the web, become cohered therewith. As the glass strands carrying web is wound upon the take-up roll or between that roll and the last furnace, the web with the filaments thereon is preferably 'sub'ected to a ressure roll a; which ma be heated or not according to the resin employed to produce a uniformity of engagement between the resin impregnated glass filaments and the fibrous Web.

The coupling agent, combined with the resinous material as applied to the glass filaments as they issue from the bushings, may be supplied through a series of sprayers 9, as shown in the drawing, or may be applied in any other suitable manner. T re particular coupling agent and resinous material employed must be compatible with the resin with which the web w was pro-impregnated. For example, there may be used vinyl tri-ethoxy' silane Where polyesters or other unsaturated resins are used and gamma amino propyl tri-ethoxy silane-where epoxy, melamine, or phenolic resins are used. In any event the coupling agents employed may be any of those known to the art to function as cohering agents or produce crosslinking action with the resin with which the web was preimpregnated. The phenomenon of cohesion of glass filaments, yarns, and the like to a resinous material is Well understood by those skilled in the art and does not here require any detailed illustration.

The end product of the method of this invention is a fibrous web made as described and rolled upon the takeup roll. As it exists in this roll it embodies either an roll.

4i uncured or a partially cured resinous material which serves to cohere the glass filaments and the fibrous web into a homogeneous structure. This structure maybe stored until used and then may be'unwound from the roll and used for a. wide variety of purposes. As hereinbefore stated, it may be used in its full width or it may be longitudinally cut into strips and Wrapped about a mandrel or mold, and thereafter the resin thereof cured to produce a strong, permanent end product. These subsequent steps respecting the use of the web form no part of the present invention.

The foregoing detailed description sets forth the invention in its preferred practical forms, but the invention is to be understood as fully commensurate with the appended claims.

Having thus fully described the invention, What I claim as new and desire to secure by Letters Patent is:

1. The method of makings glass filament reinforced fibrous web which comprises the following steps, namely: feeding a fibrous Web rare-impregnated with a thermosetting resin along a predetermined path to a take-up roll, feeding to such web as it travels nascent glass filaments at a plurality of feeding stations spaced apart longitudinally of said path with the filaments fed at the successive stations transversely interspaced with the filaments fed at the preceding stations, applying to said filaments as they are to the web a coupling agent and resinous material compatible Withresin in the web, and winding the resulting fibrous-web-glass-filament assembly onto a take-up 2. Method according to claim 1, wherein the filaments fed at the several successive stations are fed from predetermined stationary positions transversely of the web.

3. Method according to claim 1, wherein the glass fila ments are fed to the Web across a sufliciently close spacing from the web that they engage the web while said filaments remain in heated condition.

4. Method according to claim 1, wherein a parting web is interleafed between the successive convolutions of the glass carrying web as said web is Wound on the take-up roll.

References (Cited in the file of this patent UNITED STATES PATENTS 

1. THE METHOD OF MAKING A GLASS FILAMENT REINFORCED FIBROUS WEB WHICH COMPRISES THE FOLLOWING STEPS, NAMELY: FEEDING A FIBROUS WEB PRE-IMPREGNTED WIHT A THERMOSETTING RESIN ALONG A PREDETERMINED PATH TO A TAKE-UP ROLL, FEEDING TO SUCH WEB AS IT TRAVELS NASCENT GLASS FILAMENTS AT A PLURALITY OF FEEDING STATIONS SPACED APART LONGITUDINALLY OF SAID PATH WITH THE FILAMENTS FED AT THE SUCCESSIVE STATIONS TRANSVERSELY INTERSPACED WITH THE FILAMENTS FED AT THE PRECEDING STATIONS, APPLYING TO SAID FILAMENTS AS THEY AS FED TO THE WEB A COUPLING AGENT AND RESINOUS MATERIAL COMPATIBLE WITH RESIN IN THE WEB, AND WINDING THE RESULTING FIBROUS-WEB-GLASS-FILAMENT ASSEMBLY ONTO A TAKE-UP ROLL. 